1. Technical Field
This invention relates to the field of surfactants. More particularly, it relates to compositions and methods of preparing novel alkylene oxide capped alkoxylates.
2. Background of the Art
Surfactants are used in the chemical and manufacturing industries for a wide variety of purposes. These include, for example, imparting or enhancing wettability and detergency in products including wetting agents, emulsifiers, rinse aids, defoam/low foam agents, spray cleaning agents, drug delivery agents, emulsifiers for herbicides and pesticides, metal cleaning agents, paints, coatings, agricultural spread and crop growth agents, stabilizing agents for latexes, paints, and paper products, and the like. One group of frequently-employed surfactants is the nonionic surfactants, and in particular, alkylene oxide capped nonionic surfactants. These capped nonionic surfactants tend to generate less foam than uncapped nonionic surfactants, making many of them useful in applications where low foam is critical, such as in mechanical washing processes, and in paint and coating products.
Unfortunately, some alkylene oxide capped nonionic surfactants exhibit poor or otherwise unacceptable biodegradability. Examples of approaches to this problem include that disclosed in U.S. Pat. No. 5,576,281 to Bunch et al., which describes an epoxy capped poly(oxyalkylated) alcohol composition represented by the formula:R1O[(CH2CHCH3)O]x(CH2CH2O)y[CH2CH(OH)R2]wherein R1 is a linear, aliphatic hydrocarbon radical having from about 4 to about 18 carbon atoms including mixtures thereof; R2 is a linear, aliphatic hydrocarbon radical having from about 2 to about 26 carbon atoms including mixtures thereof;x is an integer having a value from 1 to about 3; and y is an integer having a value from 5 to about 30. This composition is used in an automatic dishwasher composition or cleaning composition.
Another example of an epoxy-capped poly(oxyalkylated) alcohol is described in U.S. Pat. No. 5,766,371, also to Bunch et al., wherein the formula is shown as:R1O[(CH2CH(CH3))O]x(CH2CH2O)y[CH2CH(OH)R2]z wherein R1, R2, x and y are as defined in the previous paragraph; and z is an integer having a value of from 1 to about 3. Again, this epoxy-capped poly(oxyalkylated) alcohol is shown as being particularly useful in an automatic dishwasher composition.
Yet another example of an epoxy capped poly(alkoxylated) alcohol is described in U.S. Pat. No. 4,898,621, to Pruehs et al., wherein the formula is shown as:R1—(CHOH)(CHR3)(OCH2CH2)nOR2 wherein R1 is hydrogen or a linear C1-C16 alkyl radical; R2 is a linear or branched C4-C8 alkyl radical; R3 is a hydrogen or C1-C16 alkyl radical; and n is a number between 7 to 30, with the proviso that the total number of carbon atoms in R1 and R3 is 6 to 16.
Another example of an alkylene oxide capped poly(alkoxylate) is described in WO9612001 to Groom et al., wherein the formula is shown asR3O[CH2CH(CH3)O]X(CH2CHR4O)y[CH2CH(OH)R5]z wherein R3 is a linear, aliphatic hydrocarbon radical having an average of from about 4 to about 18 carbon atoms, including mixtures thereof; R4 is hydrogen or a lower alkyl having between 1 and 6 carbon atoms; and R5 is a linear, aliphatic hydrocarbon radical having an average of from about 2 to 14 carbon atoms, including mixtures thereof; x is zero or an integer having a value from 1 to about 5; y is an integer having a value from 1 to about 30; and z is an integer having a value of from 1 to about 3.
Still another example of an alkylene oxide capped poly(alkoxylate) is described in U.S. Pat. No. 4,340,766 to Klahr et al., wherein the formula is shown as:R1O—(CH2CH2O)n(CH2CH(C2H5)O)m—Hwherein R1—O is an alkanol with 8 to 20 carbon atoms; n has any value from 4 to 14; and m is a real number with values ranging from 1.6 to 2.4.
Yet another example of an alkylene oxide capped poly(alkoxylate) is described in U.S. Pat. No. 3,539,519 to Weimer wherein the formula is shown as:R1O—(CH2CH2O)n(CH2CH(C2H5)O)m—Hwherein R1—O is an alkanol with 8 to 18 carbon atoms; n has any value from 3.5 to 10; and m is a real number with values ranging from 0.5 to 1.5.
Another example of an alkylene oxide capped poly(alkoxylate) is described in U.S. Pat. No. 6,693,065 to Gentilhomme et al., wherein a surfactant of the following formula is a component of a detergent composition:R1O—(CH2CH2O)n(CH2CH(R2)O)m—Hwherein R1 is an alkyl chain with 8 to 20 carbon atoms; R2 is an alkyl radical containing 1 or 2 carbon atoms; n has any value from 8 to 15; and m is a real number with values ranging from 1 to 10.
Yet another example of an alkylene oxide capped poly(alkoxylate) is described in JP10192685 to Tatsuo et al., wherein the formula is shown as:RO(AO)m(BO)nHwherein R is a hydrocarbon group with a carbon number of 8 or 9 that has one or more side chains; AO is an oxyalkylene radical with carbon numbers of 2-3; BO expresses an octy-butylene radical; m is 6-26; and n is from 1 to 3.
Although the above compositions represent low foaming surfactants with some biodegradability, the performance of the above compositions lack desirable performance attributes such as rapid dynamic surface tension reduction, which in many cases is critical for effective cleaning.
The prior art also has examples of alcohol alkoxylates based on secondary alcohols. For example, secondary alcohol poly(alkoxylates) are described in U.S. Pat. No. 5,912,209 to Kassebaum, wherein the formula is shown as:
wherein R1 and R2 are independently straight or branched chain C2 to about C28 alkyl, aryl or alkylaryl groups and the total number of carbon atoms in R1 and R2 is about 7 to about 30; R3 is hydrogen; R4 groups are independently C1 to C4 alkylene groups; and n is an average number from about 3 to about 30.
Another example of a secondary alcohol alkoxylate is shown in European Patent 0 850 907 to Kadono et al., wherein the formula is shown as:
wherein R1 and R2 represent an alkyl group, provided that the total number of carbon atoms of R1 and R2 is in the range of 7 to 29 and the number of carbon atoms of R2 is not less than that of R1; A represents a lower alkylene group; n represents a numeral in the range of 1 to 50 on the average, provided that when n is not less than 2, the number of species of oxyalkylene group represented by AO may be either one or two or more, and that when the oxyalkyl groups have two or more species, all the oxyalkylene groups are present in the average of n; and b represents a hydrogen atom or SO3M (wherein M represents an alkali metal atom, an alkaline earth metal atom, an ammonium group or a substituted ammonium group), wherein the composition comprises from 30 to 90 mole percent of the higher secondary alcohol alkoxylate compound (X) having a methyl group for R1 and 70 to 10 mole percent of the higher secondary alcohol alkoxylate compound (Y) having an alkyl group of 2 or more carbon atoms for R1.
Despite the diversity of nonionic surfactant inventions as described hereinabove and in the art in general, biodegradability, dynamic surface tension reduction, and optimal performance have, for certain applications, heretofore remained elusive.